Air conditioning apparatus



March l5, 1949. N. A. PENNINGTON 2,464,766

AIR CONDITIONING APPARATUS Filed Jan. 12, 1946 4 Sheets-Sheet 1INVENToR, NEAL PENN/wrm,

A TTRNEK March 15, 1949. N, A, PENN|NGTQN 2,464,766

AIR CONDITIONING APPARATUS Filed Jan. 12, 1946 4 Sheets-Sheet 2 @l ifINVENTOR, NEAL A. PENN/NQTON,

Lax/@www ATTORNEY.

March 15, 1949. N A, pENNlNGTQN 2,464,766

AIR CONDITIONING APPARATUS Filed Jan. 12, 1946 4 Sheets-Sheet 3PERCENTAQE HumxDlT.

DEW PDNT TEMPERATO RE.

DPH BULB TemPERh-ruaa l PERCENTAGE Hvmmmt. @u

DEW POlNT TE MPERATURE..

DR BULB TEMPEFLTURE INVENTOR,

/VEAL A PENN/NGTON www ATTORNEY.

March l5, 1949. N. A. PENNINGTON 2,464,766

AIR CONDITIONING APPARATUS Filed Jan. 12, 1946 l 4 sheets-sheet 4Pesacamwsa Hummm?.

DEW Polm- TEMPERATQRE.

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INVENTOR, NEAL APENN/rvcavow, BY

ATTORNE Y.

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T OFFICE 2.464.166 Am coNmrromNc APPARATUS Neal A. Pennington, Tucson,Ariz., assignor of one-fifth to Robert-.11. Henley, Tiptonville, Tenn.,and one-fourth to Roger Sherman Hoar,

South Milwaukee, Wis.

Application January 12, 1946, Serial No. 640,792

33 Claims. y (01.62-139) .1 2 My invention relates to new and usefulimsaid rst variant, taken along the line 2-2 of provements inair-conditioning apparatus, and more particularly to self-containedunits for cooling individual rooms, although my invention could equallywell be used in a central air-conditioning plant for a building orresidence.

The principal object of my invention is to devise a unit for merelycooling the air, without appreciable incidental change in themoisture-content thereof; although by adding appropriate furtherelements (either conventional or inventive per se) my unit would serveto humidify, dehumidify, or otherwise change the characteristics of theair which is being treated.

Competing units of the prior art involve some refrigerant (such asFreon) cooling-coils, a piped 'circuit for the cooling medium, acompressor, and

a heavy-duty motor to run the compressor. The above-listed apparatus isthe chief cause of bulk, of initial expense, of breakdowns andconsequent upkeep expense, and of consumption of electric current.

Accordingly it is a further object of my invention to eliminate theabove-listed apparatus, and thus provide a unit which is smaller, isless expensive to build, is less expensive to keep in re- In addition tomy principal objects, above stati ed, I have worked out a number ofnovel and useful details, which will be readily evident as thedescription progresses.

My invention consists in the novel parts and in the combination andarrangement thereof, which are defined in the appended claims, and ofwhich two embodiments are exemplied in the accompanying drawings, whicharef hereinafter particularly described and explained.

Throughout the description the same reference number is applied to thesame member or to similar members.

Figure 1 is a horizontal section of the apparatus of one variant of myinvention, somewhat conventionalized, taken along the line I-I of Figure2.

Figure 2 is a vertical longitudinal section of ,Figure 1.

Figure 3 is a vertical transverse section of a l'portion of said firstvariant, taken along the line 3--3 of Figure 2.

Figure 4 is a vertical transverse section of another portion of saidfirst variant, taken along the line 4-4 of Figure 2.

Figure 5 is a horizontal section of the apparatus of a second variant ofmy invention, taken along the line 5--5 of Figure 6.

Figure 6 is a vertical longitudinal section of said second variant,taken along the line 6--6 of Figure 5.

Figure '7 is a vertical transverse section of said second variant, takenalong the line I-l of Figure 6.

Figure 8 is a vertical transverse section of a portion of said secondvariant, taken along the line 8-8 of Figure 6.

Figure 9 is a vertical transverse section of a portion of said secondvariant, taken along the .line 9--9 of Figure 6.

Figures 10, 11 and '12 are psychrometric charts, of which Figure 10shows a'psychrometric circuit of air passing through my iirst variant,Figure 1l shows a psychrometric circuit of air passing -through my firstvariant under such load conditions as to render said variant relativelyimpractical, and Figure 12 shows a psychrometric circuit of air passingthrough my second variant under the same load conditions as Figure 11,thus illustrating the greater practicability of my second variant undersuch conditions.

Referring now to Figures 1 to 4, We see that II is the main container ofthe lrst variant of my invention. I2 is an air-inlet from outdoors. I3is an air-outlet to outdoors, or to the attic space of the building.

In inlet I2, there is a fan I4, the direction of rotation and shape ofblades of which is such as Ato impel air to the left in Figure 2, intopassage I5, and thence into the room through louvres I6.

In outlet I3, there is a fan I1, the direction of rotation and shape ofblades of which is such as to impel air to the right in Figure 2,sucking exhaust air from the room through louvres I8 ingr: massage I9,and discharging this air into out- Either set of louvres, or both, couldbe made adjustable. The particular types of fans shown are known asaxial-How pressure fans, but other forms of fans or blowers could besubstituted, such for example as the type of fan shown hereinafter in mysecond variant.

'I'he reasons for these optimum speeds will be A explained hereinafter.

21 is a removable dust-mter of any conventional or inventive sort.

Shaft 26 rotates a circular pad 28, which will now be described. Withoutlimitation. but rather merely for convenience in nomenclature, this padwill be referred to as the excelsior pad.

Turning to Figure 4, we see that this excelsior.

pad comprises a hub 28, spokes 80, and a rim 3|.l Each of the sectors,bounded by the spokes and heat-absorbent (l. e. high heat-conductivity,high speciilc heat, and proper surface) such as metal wool, of which Ihave tried various sorts, including copper wool, but prefer aluminumwool. As in the case of water pad 23, but now for somewhat dierentreasons, the spokes 40 and rim 4l of this aluminum-wool pad 38 are aswide (in a direction parallel to the axis rotation of the pad) as is thepad itself. This helps to hold the stuffing in place, but is primarilyfor the purpose of preventing air-fiow outwardly radial of the pad, orfrom passage I9 to passage l5, or vice versa. In this connection, notethat bridges 43 are at least deep enough to cover one sector of the padat each end-of each bridge; thus there will always be at each end ofeach bridge at least one spoke the rim, is stuffed with excelsior 32, orany other zo place, and also serve` another purpose which will bementioned hereinafter. If desired a fine-mesh or coarse-mesh screencould be added to each face of the pad, to further help hold the stuihnginA place. Any other sort of water-absorbing rotating pad could besubstituted.

This excelsior pad 28 rotates enclosed in a casing 34, each end of whichhas two circular-segment orifices 38-31. The lower one-quarter (byheight) of the pad is immersed in water (or other volatile liquid) intank 35, which is the lower portion of casing 34. This casing 34 alsoserves to support the bearings for shaft 2S.

' covered by the bridge, thus effectively sealing oi! the two passagesfrom each other. Bridges 43 also serve to support the bearings for shaft22. If desired a fine-mesh or coarse-meshscreen could be added to eachface of the pad, to further help hold the stufng in place.

The thickness of the aluminum-wool pad will be discussed hereinafter,such discussion being the means of leading up to a statement of thereasons for my second variant.

Any other sort of highly heat-absorbent pad,

l which would permit the free and yet bamed permeation of air parallelto the pads axis of rotation, but not perpendicular thereto, and whichdoes not permit an appreciable conduction of convection of heat by thepad parallel to its axis, could be substituted.

This pad 38 rotates enclosed in a casing 44, each end of which has twosectoral orifices, separated from each other by bridge 43. Upper orifice48 connects with passage l5. Lower orifice 41 connects with passage I9.

I have found that a rotation of about 30 R. P. M.

is optimum. For the less time that any given por- Both orifices connectwith passage I9, there` R. P. M., the radiauy inward gravity now of thewater from the soaked upper portion of the periphery of the pad,distributes the water very evenly and at just about lthe right degree ofsaturation for the best evaporation. The flanges 33 confine this waterand prevent it from flowing out of the pad.

Slower rotation would permit too much inward draining, and too muchdrying out due to evaporation, and so would reduce the total amount ofevaporation. Faster rotation would not give time for the desiredevenness of distribution, and so would reduce the total amount ofevaporation.

Too fast rotation would also result in the entrainment of waterparticles by the outgoing airstream. Although, of course, we do not carewhether or not this stream is thus contaminated, these particles wouldbecome carried over into the incoming stream by the aluminum-wool pads,about to be discussed.

Shaft 22 rotates a circular pad 38, which will now be described. Withoutlimitation, but rather merely for convenience in nomenclature, this padwill be referred to as the aluminumwool pad." Turning to Figure 3, wesee that this pad comprises a hub 33, spokes 40, and a rim 4|. Each ofthe sectors, bounded by the spokes and the rim, is stued with somenon-hygroscopic air permeable non rusting substance, highly tion of thispad is exposed to each air-stream, the more heat is absorbed from orgiven oii to the air, due to the greater average temperature-differencebetween pad and air. And yet, if the pad be rotated too fast, air fromone stream is entrained and mixed with the other stream, which isusually undesirable. Still faster rotation would also interfere with thecross-flow of the air through the pad.

On the other hand,l a speeding up of this pad could be employed topartly humidity the incoming air if desired.

Stopping the rotation of the pads will effect simple ventilation.

A water-level gauge 48 serves to inform the occupant of the room whetheror not the water is at optimum level. Water can be added or drainedthrough appropriate openings (not shown); and/ or a oat-valve 49 andwater supply-pipe 58 could be employed to maintain the water at thedesired level.

The operation of the just-described first variant of my apparatus is asfollows.

Exhaust air, leaving the room through passage I9, passes through theupper portion of excelsior pad 28; wherein, by the evaporation of thewater in the excelsior. this air exchanges sensible heat for latent heatin the form of moisture, become nearly saturated (about and its dry-bulbtemperature becoming reduced nearly to its wetbulb temperature, whichremains substantially unchanged. If this air be drawn from the room, ascontemplated, its initial wet-bulb temperature (which is what determinesthe final dry-bulb temperature of the adiabatic cooling) will be lowerthan the wet-bulb temperature of the outdo'or air, thus imparting aregenerative eect on the operation; hence this source for the outgoingair is generally preferable.

The thus-cooled outgoing air then passes through the lower portion ofaluminum-wool pad 3B, extracting a large portion of the heat therefrom.The waste air then passes out into the outdoors through outlet I3 orinto the attic space.

Fresh outdoor air is meanwhile entering at the same rate through inletI2, and is iiltered by dust-lter 21. It then passes through the upperportion of aluminum-wool pad 38, which has been cooled as alreadydescribed. This aluminumwool pad extracts a large portion of thesensible heat from the incoming air, without substituting any latentheat in the form of moisture, i. e., without altering the dew-point of.the incoming air.

The thus-cooled, but not humidifled, incoming air then passes on throughpassage l5 into the room which is being -air-conditioned.

Now, in order for my machine to operate in a steady state, the heatgiven .to the aluminum- Wool pad by the incoming air stream must equalthat given up by this pad to the outgoing air stream. Hence, if the twostreams are of the same magnitude, ythe incoming stream will decrease indry-bulb temperature, within the upper portion of this pad, -by the sameamount as the outgoing stream increases in dry-bulb temperature, withinthe lower portion of this pad.

I have empirically worked out the following rough rule of thumb fordetermining what thickness of aluminum-wool pad is necessary toaccomplish any given desired heat transference: namely that I have foundthat, at an air veiocity of about 600 feet per minute, and a padrotation of about revolutions per minute, an anhydrous cooling of aboutone degree Fahrenheit per inch of -pad thickness yper degree of mean.temperature difference between the pad and each air-stream can beexpected. This formula is, however, presented here not so much as aquantitative guide to the designing of machines of the sort invented byme, but rather for purposes of comparison in discussing the Ap-atentablediierences between the two variants herein discussed. This formula ispredicated upon the assumption of Ipractically perfect counterow, whichis attainable by my invention. The corresponding formula for thethickness of the excelsior pads is rather dierent. The water in one ofthese pads will acquire and maintain an equilibrium temperature equal tothe wet-bulb temperature which the outgoing air has at the pad, and thistemperature will be considerably less than the dry-bulb temperature ofthe air as it enters the pad, and even somewhat less than the dry-bulbtemperature of the air as it leaves the pad. The average 4temperaturedifference between air and water in the pad is the logarithmic mean ofthese two dierences. Dividing the isowet-bulb cooling in dry-bulbdegrees eiected by the pad, by this logarithmic mean, and thenmultiplying by 0.8, gives us a conservative thickness for the pad.Furthermore, inasmuch as the excelsior pads interpose practically noresistance to the air-stream (as contrasted with the aluminum-woolpads), I build of uniform thickness the excelsior pads of my multipadvariant.

To illustrate the application of the aluminumwool pad formula let usconsider how to design one of my machines to meet a given situation.

"Let us suppose that we wish .to cool outside air 'of 100 dry-bulbtemperature and a '54 dewpoint, so as to bring to a room which (because-of size, leakage and non-insulation) would impose a 5 load on a machineof the rate of airdelivery contemplated. This means that we must coolthe incoming air 25, to 75.

This cooling is represented by the line from A to B on Figure 10, theload being represented by the line from B to C.

The outgoing air is represented at C. The excelsior pad cools this airadiabatically (i. e., without change in wet-bulb temperature) to 95%humidity (which is about the practical capacity of such a method ofevaporative cooling): i. e., 64.8 dry bulb, represented by D. This air,in then passing through the lower half of the aluminum-wool pad, absorbsexactly the same amount of heat from the ypad as the upper half of theypad absorbed from the incoming stream, and its dry bulb thus risesanhydrously to 89.8, represented by E.

Let us now apply the formula. The mean temperature difference betweenthe aluminum-wool pad and each air-stream is 5.1 (i. e., DB/2). Thetemperature change is 25. The thickness of the pad in inches shouldaccordingly be 25 divided by 5.1: i. e., 4.9 inches, thus requiring theair in its complete circuit to traverse a total aluminumwool padthickness of 9.8 inches. This is a wholly feasible pad-thickness.

But suppose that (due to greater size, and/or leakage, and/'or lack ofinsulation) the room imposed a load of (say) 12.

We must now cool the incoming air to 68, in order to maintain atemperature of 80 within the room. See Fig. 11. Points A, C, and D arethe same, but B' and E are different. temperature diierence is now 1.6,and the temperature change is 32, a total traverse of 40 inches. So thepad has to be 20 inches thick.

This is approaching prohibitive thickness, largely due to the increasedresistance to air at the required velocities.

This brings us to my second variant, which although generically the sameas my first variant, em-ploys an additional principle which I calltemperature cut-back.

Referring now to Figures 5 to 9, we see that 5l is the main container ofthe second variant of my invention, 52 is an air-inlet from outdoors 53is an air-outlet to outdoors, but might instead discharge into the atticspace of the building.

54 is a divided-impeller squirrel-cage centrifugal fan, one half ofwhich serves to suck air in through inlet 52, and the other half ofwhich serves to drive air out through outlet 53. Two separate fans ofthis or some other type could be substituted. A motor 55 serves to drivefan 54.

The outgoing air is sucked out through passage 55. The incoming air isdriven inthrough passage 5l. 1

Motor 55. through self-contained gear-reduction 58, and sprocket drive59, drives shaft 50 at the optimum speed of about 30 R. P. M., alreadydiscussed. Shaft 60, through sprocket drive SI, drives shaft 62 at theoptimum speed of about 3 R. P. M., already discussed.

63 is a removable dust-filter of any conventional or inventive sort.

Shaft 60 rotates two circular pads 64, 65 of the same sort as thealuminum-wool pa described in detail in connection with my firstvariant. Figure 8 shows an elevation of one of these pads, andillustrates the two air passages 56, 51 through which it rotates.

The mean Shaft 62 rotates two circular pads 6B and 61 of the same sortas the excelsior pad described in detail in connection with my iirstvariant. Figure 9 shows an elevation of one of these pads, andillustrates the air passage 56, and tanks 68 and 69 through which itrotates. Inasmuch as the water in each of pads 66 and 61 should acquireand maintain in operation an equilibriumtemperature equal to thewet-bulb temperature which the outgoing air-stream has at the respectivepad, and as these two wet-bulb temperatures are seen by Figure 12 to bequite distinct. these tanks should be separate, for the very bestresults; but this is not imperative.

The operation of my second variant is as follows.

Exhaust air, leaving the room through passage 56, passes through theupper portion of excelsior pad 66; wherein, by the evaporation of thewater in the excelsior, this air exchanges sensible heat for latent heatin the form of moisture, becoming about 95%l saturated, and its dry-bulbtemperature becoming reduced nearly to its wet-bulb temperature, whichremains substantially unchanged.

The thus-cooled outgoing air then passes through the lower portion ofaluminum-wool pad 64, extracting a portion of the heat therefrom, andcorrespondingly having its own drybulb temperature raised thereby, withno appreciable alteration in its own moisture content.

This air now has quite different characteristics from what it had whenit left the room, being now of a much higher dewpoint than before, and(usually) of a somewhat higher drybulb temperature, depending on suchconsiderations as the initial temperature of the incoming air, the load,the desired amount of cooling to be effected by the machine, and therelative thickness of the two aluminum pads. All this will behereinafter discussed.

This exhaust air now passes through the upper portion of excelsior pad61; wherein, by the evaporation of the water in the excelsior, this airexchanges sensible heat for latent heat in the form of moisture,becoming about 95% saturated, and its dry-bulb temperature becomingreduced to nearly its wet-bulb temperature, which remains substantiallyunchanged.

The thus-cooled outgoing air then passes through the lower portion ofaluminum-wool pad 65, extracting a. portion of the heat therefrom.

The exhaust air is then discharged, by being sucked in through the openleft hand (in Figure 7)')end of fan 54, and being thereby blown outthrough air-outlet 53.

Fresh outdoor air is. meanwhile entering at the-'same rate throughair-inlet 52, being sucked in through the open right hand (in Figure 7)end of fan 54, and being thereby blown out into passage 51.

Here it is filtered by passing through dustlter 63. It then passessuccessively through the upper portion of aluminum pad 65 and throughthe upper portion of aluminum pad 64, each of which has been cooled asalready described. Each pad extracts a portion of the sensible heat fromthe incoming air, without substituting any latent heat in the form ofmoisture, i. e. without altering the dew-point of the incoming air. Theamount of the dry-bulb cooling of the incoming air by each aluminum-woolpad is exactly the same as the amount of cooling of that pad by theoutgoing air.

The thus cooled, but not humidiiied, incoming air then passes on throughpassage 51 into the room which is being air-conditioned.

If it is desired to partially humidity the incoming air, this can beaccomplished by bypassing some of the moist outgoing air from outlet 53into inlet 52 through cross-conduit 10.

From the fact that my thus described second variant differs essentiallyfrom my earlier described rst variant by having two aluminumwool padsinstead of one, and two excelsior pads instead of one, it might beerroneously supposed that we have in the second variant a mereduplication of parts or a mere division of parts.

That this is not so structurally is seen by the fact that my secondvariant does not substitute two aluminum-wool pads in the place whereone grew before, nor two excelsior pads in the place where one grewbefore. Nor is each pad of my first variant divided into two, in place,in my second variant.

But, instead, by alternating the aluminumwool pads with the excelsiorpads, I obtain a new i arrangement which is beyond mere duplication ormere division.

In fact two of my type 1 machines hitched together in series would besomething quite different again from my type 2 machine, although eventhis would not constitute a true duplication. True duplication wouldconsist in bitching together two of my type 1 machines in parallel, soas to air-condition twice as large a room.

Furthermore, a psychrometric comparison of my two variants shows thatthey differ in kind, quite distinctly.

To illustrate this, let us now turn to Figure 12, and see how thissecond variant of mine solves the problem of Figure 11, namely: outsideair at 100 dry bulb, 54 dew point; load 12; desired room temperature 80.

The right-hand aluminum pad anhydrously cools the incoming air from M t0N, and the lefthand aluminum pad 64 cools it further from N to O. Theroom load heats it, from O to P. It is then cooled adiabatically by theleft-hand excelsior pad 66 from P to Q, and in turn cools the left-handaluminum pad 64 from Q to R (equal and opposite to NO). It is thencooled adiabatically by the right-hand excelsior pad 61 from R. to S,and in turn cools the right-hand aluminum pad 65 from S to T.

Points M, O, P and Q are fixed by our initial hypotheses. Any givenchoice of point N fixes points R, S, and T. If we juggle N on apsychrometric chart blank until ON/QO equals NM/SN, then the two padswill be of equal thickness (2 ON/QO each), and their sum will be at theminimum. This fact (mathematically demonstrable), plus considerations ofmass production and replaceability of parts, renders it desirable tohave the two pads be exact duplicates. My two excelsior pads aresimilarly made identical.

' From Figure l2 we see that the mean temperature difference in pad 64is 1.6 and the temperature drop is 8.4". In pad 65, these two gures are4.5 and 23.6, respectively. So, applying the pad-thickness formula givenearlier herein, each pad need be only 5.25 inches thick, a totaltraverse of 21.0 inches, as compared with 40.0 inches in my rst varianton Figure 11, under identical assumed conditions. Obviously 21.0 inchesoffers much less resistance to air than 40.0

Surely the obtaining of the same results with two pads involving a totaltraverse of 21.0 inches as with one pad involving a total traverse of40.0 inches, the psychrometric circuits being seen at a glance to bequite different for the two typesoi machines, is a proof that we haveneither dou.

bled nor split our original single pad.

The use of three aluminum-wool pads and' suggested, or as a basis for agood start of thejuggling, the following approximate formulas are veryclose.

Let C=tota1 cooling desired, in dry-bulb degrees.

And T=onehalf the dierence between the dry-bulb temperature of theincoming air as it enters the room, and 1 plus the wet-bulb temperatureof the outgoing air as it leaves the room.

Then the second cooling in .dry bulb degrees is -3T,

And the thickness of each pad in inches, is that expression divided byT. y

From a study of the charts it may be noted that neither variant of myinvention can reduce the dry-bulb of the incoming air to below onedegree higher than the wet-bulb which the outgoing air has as it leavesthe room. But this limitation does not discredit either type, for it.constitutes merely an indication of as to when a given size of unit istoo small for a given job.

It should be noted that, 1n both variants, the

incoming air-stream flows through each aluminum-wool pad in the oppositedirection from the flow of the outgoing air-stream, andai; practicallyidentically the same speed. Furthermore, at the optimum speed of padrotation, and on account of the very small thickness of the individualaluminum filaments, the heat absorbed by the wool in the hot part of thepads cycle of rotation does not have time to travel by conductionlongitudinally of the individual ilaments, or from lament to filament,an appreciable distance, before being given up in the cold part of thecycle, and hence remains at substantially the same point in the pad ineach of the two airstreams. And the fact that the pad rotates so thateach particle thereof is carried in a plane perpendicular to theairflow, prevents any conveying of heat by the pad except perpendicularto the airflow. These factors result in the mean temperature dierencebetween either air-stream and the wool at any given depth being equal toone half the temperature diil'erence between the two streams at eithersurface of the pad: i. e., practically ideal counteriiow.

This counterow is indicated, both by practical experience and bytheoretical analysis, to be at least highly advisable, and perhaps evenabsolutely essential.

It should be noted that, in order to attain the advantages which Iobtain from counterflow, it is necessary not only to ow my twoair-streams in opposite directions, but also to ow them in oppositedirections through a means of heat-exchange in which there is noappreciable conduction or convection of heat parallel to the directionof the airiiow.

The importance of such counterflow cannot be overemphasized, for suchcounterflow enables' each anhydrous heat-exchange between incoming airand adiabatically cooled outgoing air to remove heat from the incomingair to an extent impossible in any system in which there is anyaveraging of temperature in the heat-exchange means parallel to thedirection of iiow of. the air. Such averaging can occur by the use ofcool- 10 ing or heating coils, or by the use oi' random flow ofnon-hygroscopic cooling-heating fluid in pads, or even (although such110W of uid in pads be strictly perpendicular to the flow of the airtherethrough, and hence no averaging takes place within either pad), bycommingling the fluid as it passes from pad to pad.

In a thoroughly averaging system, the absolute limit of cooling theincoming air by any one heatexchange is half of the difference betweenthe temperature at which the incoming air enters the heat-exchanger andthe temperature at which the adiabatically cooled outgoing air entersthe heat-exchanger, and even this theoretic limit is not practicallyattainable. Even if the averaging of temperature takes place only as thecoolingheating fluid passes from pad to pad, the absolute limit isincreased merely to two-thirds the abovementioned difference. Whereas ina counterflow system of the sort contemplated by me, the limit is thetemperature at which the adiabatically cooled voutgoing air enters theheat-exchanger, and it is quite practical to cool the incoming air towithin a very few degrees of this limit.

This full advantage of counterflow cannot be attained in any averagingsystem, but can be attained in my apparatus.

From the foregoing description it should be clear that either of my twodevices will do everything of which the prior art competing devices arecapable, and yet takes up less space, and requires less initial cost,less upkeep, and less operating current.

In the claims, when I use the term tank, I intend a tank capable ofholding water or other similar volatile liquid, for the purposedescribed.

In theclaims, I shall refer to the excelsior pad generically as an"air-permeable evaporativeliquid-holding pad; and to the aluminum-woolpad generically as an air-permeable non-hygroscopic pad highly heatabsorbent.

Having now described and illustrated two forms of my invention, I wishit to be understood that my invention is not to be limited to the specicforms or arrangements of parts herein described and shown.

For example, if desired, appropriate additional passages and valvescould be added, so that optionally part or all of the outgoing air couldbe drawn from outdoors.

Furthermore, other air-conditioning elements could be added.

My multipad variant is preferable where the cooling load is heavy,and/or in fixed installations. My single-pad variant is preferable wherethe requirement of a small compact moveable set is paramount.

I claim:

l. In an air-conditioning unit, the combination of: two air-passages; atank; a pad comprising sectors of air-permeableevaporative-liquid-holding material, this pad being rotatably mounted insuch manner as to carry each sector of the pad successively through thetank beneath the liquid level therein and across the rst air-passage; apad comprising sectors of air-permeable non-hygroscopic highlyheat-absorbent material, this pad being rotatably mounted in such manneras to carry each sector successively across each of the two passages;means for rotating the two pa-ds; means for impelling a stream of air inthe rst passage, first through the evaporative-liquidholding pad andthen through the nonhy-- groscopic pad, whereby this stream of air maybe first cooled by evaporation and then may cool` the 'non-hygroscopicpad; and means for impell' ing air in the second passage through thenonhygroscopic pad, whereby this second stream of air may be anhydrouslycooled by the non-hygroscopic pad, and may then pass into,the enclosureto be conditioned.

2. An air-conditioning unit, according to claim 1, further characterizedby the fact that the evaporative-liquid-holding pad comprises a rim andspokes, all of substantially the same width in an axial direction, andhaving on each face anges projecting into the sectors bounded thereby.

3. An air-conditioning unit, according to claim 1, further characterizedby the fact that the evaporative-liquid-holding pad comprises a rim andspokes, all of substantially the same width in an axial direction, and apacking of excelsior in the sectors between spokes and rim.

4. An air-conditioning unit according to claim 1, wherein theevaporative-liquid-containing pad and the non-hygroscopic pad are sodrivably connected to the means for rotating them that, when the formeris rotated at approximately 3 R. P. M., the latter is rotated atapproximately 30 R. P. M.

5. In an air-conditioning unit, the combination of: two air-passages;means for impelling a separate stream of air through each air-passage;means for adiabatically cooling the air-stream in the rst passage, bythe evaporation of water therein; a pad comprising sectors ofair-permeable non-hygroscopic highly heat-absorbent material, rotatablymounted in such manner as to carry each sector successively across eachof the two passages, this pad lying in the rst passage downstream fromthe adiabatic cooling means; and means for rotating this pad; wherebythe pad may be cooled by the cooled air in the first passage, and inturn may anhydrously cool the air in the second passage.

6. An air-conditioning unit according to claim 5, in which theheat-absorbent material of the rotating pad is metal wool held in rigidformation, and in which there are means to prevent the bypassing of airfrom passage to passage through or around this pad, and in which eachair-stream passes through this pad in a sense opposite to that of theother air-stream.

7. An air-conditioning unit according to claim 5, in which theheat-absorbent material of the rotating pad is aluminum wool held inrigid formation, and in which there are means to prevent the by-passingof air from passage to passage through or around this pad, and in whicheach air-stream passes through this pad in a sense opposite to that ofthe other air-stream.

8. An air conditioning unit, according to claim 5, further characterizedby the fact that each airstream passes through the non-hygroscopic padin a direction parallel to its axis of rotation, and in a sense oppositeto that of the other air-stream.

9. A rotatable pad for an air-conditioning unit, packed with metal wool,in combination with means for passing two separate and distinctairstreams therethrough, for transfer of heat from one stream to theother.

10. In an air-conditioning unit, the combination of two air-passages;liquid-containing means; a plurality of pads each comprising sectors ofair-permeable evaporative-liquid-holding material, each pad beingrotatably mounted in such manner as to carry each sector of the padsuccessively through the liquid-containing means beneath the liquidlevel therein and across the iirst air-passage; a plurality of pads eachcomprising sectors of air-permeable non-hygroscopi'c highlyheat-absorbent material, each pad being rotatably mounted in such manneras to carry each sector successively across each of the two passages;means for rotating all the pads; means for impelling air in the firstpassage, first through one evaporative-liquid-holding pad, then throughone non-hygroscopic pad, and so on alternately, whereby this stream ofair is alternately cooled by evaporation and then cools anon-hygroscopic pad; and means for impelling air in the second passagethrough the non-hygroscopic pads successively, whereby this stream ofair is an-` hydrously cooled by the non-hygroscopic pads, and thenpasses into the enclosure to be conditioned.

11. An air-conditioning unit according to claim 10, wherein thenon-hygroscopic pads are all of substantially the same thickness.

12. An air-conditioning unit, according to claim 10, furthercharacterized by the fact that each air-stream passes through eachnon-hygroscopic pad in a direction parallel to its axis of rotation.

13. An air-conditioning unit, according to claim l0, furthercharacterized by the fact that each air-stream passes through eachnon-hygroscopic pad in a direction parallel to its axis of rotation, andin a sense opposite to that of the other airstream, and that eachair-stream passes through. the non-hygroscopic pads in an order oppositeto that of the other air-stream.

14. An air-conditioning unit according to claim 10, wherein theliquid-containing means for each evaporative-liquid-holding pad isdistinct.

15. An air-conditioning unit, according to claim 10, furthercharacterized by the fact that each air-stream passes through eachnon-hygroscopic pad in a direction parallel to its axis of rotation, andin a sense opposite to that of the other air-stream, and that eachair-stream passes through the non-hygroscopic pads in an order oppositeto that of the other air-stream, each non-hygroscopic pad beingcharacterized' by being incapable of appreciable conduction orconvection of heat thereby in a direction parallel to the axis ofrotation of the pad,'and by being incapable of appreciable airowtherethrough in a plane perpendicular to its axis of rotation.

16. An air-conditioning unit according to claim" 5, in which theheat-absorbent material of the rotating pad is of such structure that noappreciable conduction or convection of heat thereby' parallel to thedirection of airflow therethroughl will take place during one rotationof the pad, and in which there are means to prevent the by passing ofair from passage to passage through or around this pad, or radiallyoutwardly from this pad, and in which each air-stream passes throughthis pad in a sense opposite to that of the other air-stream.

17. -An air-conditioning unit according to claim 10, in which theevaporative-liquid-holding means is water-holding means, and theliquid-containing means is water-containing means.

18. In an air-conditioning unit, the combination of two air-passages; aplurality of evaporative air-cooling elements, located in the firstair-passage; a plurality of pads each comprising sectors ofair-permeable non-hygroscopic highly heat-absorbent material,alternating with the' cooling elements; each pad being rotatably mountedin such manner as to carry each sectori successively across each of thetwo passagesy means for rotating the pads; means for impelling a streamof air in the first passage, iirst throughl onecooling element, thenthrough one non-hygroscopic pad, and so on alternately, whereby thisfirst stream of air may be alternately cooled by evaporation and thenmay cool a non-hygroscopic pad; and means for impelling air in thesecond passage through the non-hygroscopic pads successively, wherebythis stream of air may be anhydrously cooled by the non-hygroscopicpads, and then may pass into the enclosure to be conditioned.

19. The process of conditioning outdoors air for use in an enclosure, byheat but not moisture exchange with air extracted from the enclosure,which comprises: impelling a stream of air into a, passage; thereinanhydrously reducing the drybulb temperature of said air a given amount,by a heat-exchange with the outgoing air; and then passing thethus-cooled air into the enclosure; extracting a stream of air from theenclosure into a second passage; adiabatically reducing the dry-bulbtemperature of said stream of outgoing air by evaporating a liquidtherein, to below the dry-bulb temperature which the incoming air hadwhen anhydrously cooled as above; and nally anhydrously increasing thedry-bulb temperature of said outgoing air, by heat-exchange with theincoming air, an amount equal to the reduction of dry-bulb temperatureof the incoming air effected by that same exchange, the range ofdry-bulb change of the incoming air effected by this exchangeoverlapping the range of dry-bulb change of the outgoing air more thanone half.

20. The process of conditioning outdoors air for use in an enclosure, byheat but not moisture exchange with air extracted from the enclosure,which comprises: impelling a stream of air into a passage; thereinanhydrously reducing the drybulb-temperature of said air a given amount,by a rst and a second heat-exchange with the outgoing air; and thenpassing the thus-cooled air into the enclosure; extracting a stream ofair from the enclosure into a second passage; adiabaticaily reducing thedry-bulb temperature o said stream of outgoing air, by evaporating aliquid therein, to below the dry-bulb temperature which the incoming airhad when cooled by the second of the two cooling steps mentioned above;anhydrously increasing the dry-bulb temperature of said outgoing air, bythe second heat-exchange with the incoming air, an amount equal to thereduction of dry-bulb temperature of the incoming air effected by thatsame exchange, the range of dry-bulb change of the two streams effectedby this exchange overlapping each other more than one half;adiabatically reducing the drybulb temperature of said stream ofoutgoing air, by evaporating a liquid therein, to below the drybulbtemperature which the incoming air had when cooled by the iirst of thetwo cooling steps mentioned above; and finally anhydrously increasingthe dry-bulb temperature of said outgoing air, by the rst heat-exchangewith the incoming air, an amount equal to the reduction of dry-bulbtemperature of the incoming air efected by that same exchange, the rangeof drybulb change of the incoming air elected by this exchangeoverlapping the range of dry-bulb change of the outgoing air more thanone half.

21. In a heat-exchanger for an air conditioning unit, the combination ofI two parallel air-passages; means for impelling air in' one directionthrough one of these two passages; means for impelling air in theopposite direction through the other of these two passages; a padcomprising 14 sectors of air-permeable non-hygroscopic highlyheat-absorbent material, this pad being rotatably mounted in such manneras to carry each sector of the pad successively across each of the two 1passages, the material being such and so packed that there can be noappreciable conduction of heat by the pa-.i axially thereof in the timeof one rotation; means to prevent appreciable leakage of air radiallyfrom the pad; means to prevent appreciable leakage of air from onepassage to the other angularly through the pad; and means to preventappreciable leakage of air from one passage to the other by by-passingthe pad.

22. Apparatus according to claim 9, further characterized by the factthat the two air-streams pass through the pad in parallel and oppositedirections.

23. In an air-conditioning unit, the combination of two air-passages; anair-permeable evaporative-liquid-holding pad, extending across the firstpassage; means to continuously supply evaporating liquid throughout thispad; a pad comprising sectors of air-permeable non-hygroscopic highlyheat-absorbent material, this pad being rotatably mounted in such manneras to carry each sector successively across each of the two passages;means for rotating this latter pad; means for impelling a stream of airin the rst passage, rst through the evaporativeliquid-holding pad andthen through the nonhygroscopic pad, whereby this stream of air may befirst cooled by evaporation and then may cool the non-hygroscopic pad;and means for impelling air in the second passage through thenonhygroscopic pad, whereby this second stream of air may be anhydrouslycooled by the non-hygroscopic pad, and may then pass into the enclosureto be conditioned.

24. An air-conditioning unit, according to claim 23, furthercharacterized by the fact that the evaporative-liquid-holding padcomprises rigid elements to hold rigid the form of the pad, and.

water-absorbent air-permeable material supported thereby.

25. An air-conditioning unit, according to claim 23, furthercharacterized by the fact that the evaporative-liquid-holding padcomprises rigid elements to hold rigid the form of the pad, and apacking of excelsior supported thereby.

26. An air-conditioning unit, according to claim 23, furthercharacterized by the fact that the nonhygroscopic pad comprises rigidelements to hold rigid the form of the wheel, and non-hygroscopicair-permeable material highly heat-absorbent supported thereby. i

27. An air-conditioning unit, according to claim 23, furthercharacterized by the fact that the nonhygroscopic pad comprises a rimand spokes, all of substantially the same width in an axial direction,and a packing of non-hygroscopi airpermeable material highlyheat-absorbent in the sectors between spokes and rim, the packing beingheld axially immovable with respect to the rim and spokes.

28. An air-conditioning unit, according to claim 23, furthercharacterized by the fact that the non-hygroscopic pad comprises rigidelements to hold rigid the form of the wheel, and metal wool rigidlysupported thereby.

29. An air-conditioning unit, according to claim 23, furthercharacterized by the fact that the non-hygroscopic pad comprises rigidelements to hold rigid the form of the wheel, and aluminum wool rigidlysupported thereby.

30. An air-conditioning unit according to claim 28, in which the airpassages and impelling means each stream of air will pass through saidpad at 5 and spokes, and by having adjacent each face of 15 this pad aixed transverse bridge between the two air-passages, each half of thisbridge having a shape and area at least equal to the shape and area ofone sector of the pad.

32. An air-conditioning unit, according to claim 2o Number 23, furthercharacterized by the fact that each air-stream passes through thenon-hygroscopic pad in a direction parallel to its axis of rotation.

33. An air-conditioning unit, according to claim 23, furthercharacterized by the fact that each 25 16 air-stream passes through thenon-hygroscopic pad in a direction parallel to its axis of rotation, andin a sense opposite to that of the other alrstream.

NEAL A. PENNINGTON.

REFERENCES CITED The following references are of record in the ille ofthis patent:

UNITED STATES PATENTS Number Name Date 1,510,340 Pauls Sept. 30, 19241,762,320 Wood June 10, 1930 2,075,036 Hollis Mar. 30, 1937 2,083,436Bothezat June 8, 1937 2,361,692 Karlsson et al Oct. 31, 1944 FOREIGNPATENTS Country Date 134,256 Great Britain Oct. 27, 1919 387,517 GreatBritain Feb. 9, 1933 548,400 France Oct. 20, 1922 148,763 Germany Mar.10, 1903

